Ladders are a very integral part of our society, such a simple device, they have been around for thousands of years and can today be found at just about any household in much of the world, as well as any factory, ship, on the back of recreational vehicles, and on the roof of many work trucks. Yet new forms and functions for ladders are being developed still. There are permanent ladders suspended by being fastened to a surface like a wall of a building, portable extension type ladders that are supported on the ground and lean against a surface, or portable self stabilizing ladders having collapsible pivotal props or more commonly known as a step ladder that also rest on the ground. What isn't available until now is a combination of a portable ladder and fixed suspended ladder, or rather a portable self supporting ladder that can optionally be suspended simulating a permanent type ladder.
The portable ladder as referenced throughout this document includes a ladder of rigid construction that can be easily carried by one person of normal dexterity and the ladder is self supporting, intentionally usable for human ascension by resting the bottom of the stiles (and pivotal props if included) on a surface such as the ground. No other vertical support is required during independent use, although a portable ladder without a prop will require a surface to lean against during use.
It will be of great public convenience and safety to have available a suspended portable ladder on the back of an rv (recreational vehicle) for example, that would allow access to the roof of the rv and also provide for storage and transportation of the ladder, yet have the portable ladder mounted using an apparatus that would make it simple to remove the ladder and use it independent of the attached mode, to wash a window or fix a light, hang a clothes line or hammock. As opposed to precariously standing on tables or chairs to accomplish such tasks. Another potential embodiment would be for a technician fixing a large metal working machine in a factory whose control components are on top of a moving portion of the machine. If a portable ladder was stored using the apparatus on the moving column of the machine the technician could readily have access to those controls or additionally un-attach the affixed portable ladder for vertical access to another part of the machine without needing to hunt down a portable ladder, promoting efficiency and good co-worker relations. Similarly in a residence, instead of a permanent drop down type attic ladder, this apparatus would permit not only ladder storage, but also access to the attic if mounted adjacent the attic access ceiling hole present in many homes. Then additionally the homeowner would have available a portable ladder for changing light bulbs or batteries in smoke detectors at other locations without needing a second ladder, or dangerously standing on buckets or chairs to accomplish such tasks. Yet another benefit of such a device is the fact that mounting a removable ladder as opposed to a non-removable one would not require extensive consideration of placement because if an access panel or in the case of a vehicle if an engine compartment access door was blocked, the ladder could be easily removed providing access of the door or panel. Furthermore if it was desired to prevent access to an elevated area this device could permit removal of the ladder so no such access was available, then install the ladder when access was required.
There is an overwhelming array of art generally referred to as ladder supports that hold the top of an extension ladder away from a desired surface for access around building overhangs or to hold a worker away from the surface making it easier to work such as U.S. Pat. No. 4,615,412, or GB2386920. Some of these types are referred to as safety devices because they are fastened to the structure and hold the ladder from sliding sideways such as U.S. Pat. No. 2,256,452, U.S. Pat. No. 6,578,665, and W003100204. A few go a little further like GB1530117, EP1087098, GB623906, U.S. Pat. No. 6,533,069, U.S. Pat. No. 6,029,774, and attempt to prevent the ladder from falling away from the wall. But none of these suspend the ladder off of the ground. The bottom of the ladder must make contact with the ground for support which would be a problem if the ground was not level, soft, unstable or even moving such as on a vehicle. Also if space was an issue, placing the feet of the ladder at a substantial distance of the surface may be hazardous or not possible. If an attempt was made to suspend a ladder in one of these referenced devices, none of them have a means of holding the lower portion of the ladder at a distance of the wall duplicating the upper distance, so during use the suspended ladders incline angle would be dangerous. Your feet would be closer to the surface than your torso, you would be trying to climb while gravity would be pulling you backwards. Not to mention the risk of failure of the attachment as it was not intended to support the complete weight of a ladder and user. It was also concerning to realize the safety devices that prevent ladder movement require a non braced unsafe ladder to be used for installation of the invention.
U.S. Pat. No. 4,211,306 does suspend the ladder properly during use and the ladder sections are removable, but this is a fire escape device and the removed ladder section must be stored near the mounting bracket. This ladder bracket combination does not provide a portable ladder but rather a ladder section that can only be used if attached to it's mating bracket, it is not usable away from the mounted position. Additionally, if someone foolishly attempted to use the ladder section as a portable ladder and a fire occurs, the ladder would not be present to perform it's stated purpose.
Another prior art consideration was a “hook-top” ladder that hangs on hooks integrated into the top of the ladder. These are readily available at many industrial supply companies such as McMaster(mcmaster.com, search “hook top ladder”). This type of ladder is suspended over walls by means of hooks integrated into the top of the ladder, but does not provide safe use unless in the hung configuration, this is not a portable ladder as referred herein. Also all of these devices are meant only for use during incline and none provide a suitable storage location for a ladder when it is not in use.
Similarly there is also a vast array of vehicle mounted ladders such as U.S. Pat. No. 4,245,716, U.S. Pat. No. 5,046,582, U.S. Pat. No. 6,264,222, U.S. Pat. No. 6,378,654, GB2384812, but these devices lack in their ability to be removed, so they can't be used at other locations, they are not portable. GB2360315, JP2002274270, U.S. Pat. No. 4,431,082, FR2729900, JP9240375 are all examples of vehicle ladders that are removable, but none permit the use of the ladder other than when mounted to the vehicle. Again, they are not portable ladders as referred herein. If vertical access is required at a different location other than the mounted location an additional ladder would be needed or the person would need to improvise using a box, or bucket, or other dangerous means. Also these ladder support methods do not provide a storage or transportation location for the ladder in the mounted usable configuration. If using one of these ladders the operator would need to install the ladder for use, then remove it and store it for transportation, then re-install it for use again, a very inconvenient proposition.
Inventions U.S. Pat. No. 6,250,425, U.S. Pat. No. 6,357,548, U.S. Pat. No 4,408,680 are also vehicle mounted portable ladder support devices, and although they support a portable ladder for use they do not suspend the ladders nor do they provide for storage or transportation in this usable position. The ladders must be removed or re-configured during vehicle movement then set up again at the new location. Another concern with these devices is the fact that the method of support is such that the ladders are cantilevered, not being supported properly for their design. During use a lot of stress is placed on the ladders stiles at the locations where the stiles are supported by these devices, so much leverage could cause the ladders to fail, or break near these contact points causing serious damage and injury.
The dual location ladder of FR2828522 is a very nice idea, although it isn't a ladder suspension apparatus, nor a portable ladder, but rather a ladder that pivots and is supported on the ground to be used at only the two locations provided, namely the bunk area and the rear of the recreational vehicle. With space being of value in a recreational vehicle, storage and transportation of the ladder inside the vehicle may not be desired. Also, often such bunk ladders are not taken during trips if the occupants won't be using the bunk, or children who could be lifted by a parent will be using the bunk area. But without the ladder, roof access isn't possible. And because suspension means are not provided the ladder can't be transported outside the vehicle. Additionally, this is only for a class c style rv with a bunk overhead. Many rv's have no need for a bunk ladder, but do need access to the roof as well as a portable ladder for other tasks which this device will not accommodate.